"I know that various modifications have been applied and let's hope that means all of us drivers can race in safe conditions," Alonso said. "At the moment, we can't make any predictions, because no one has tried them and we don't know what and how many benefits they can bring, apart from trusting in the fact that it won't be dangerous to race."

Vettel has never won in Germany; in fact he hasn't won in Europe in 22 months.

At Silverstone, Vettel retired when leading in the closing stages due to a gearbox breakdown. But he still leads the championship after eight of 19 races and has three wins this season.

The German has 132 points but Alonso cut the gap in Britain and has 111.

"We have to regain the lost points as soon as possible," Vettel said.

Rosberg, who has won two of the past three races, said he wasn't that concerned with the choice of tires.

"With the car we have it doesn't matter which tires we use because we have a very quick car in general so I am confident we can stay where we are, more or less," Rosberg said.